The addition reaction of diamides to 1,2,5-thiadiazole 1,1-dioxide derivatives

The reactions of several derivatives of 1,2,5-thiadiazole 1,1-dioxide [3,4-diphenyl-(1a), 3,4-bis(p-methoxyphenyl)-(1b), phenanthro[9,10-c]-(1c) and acenaphtho[1,2-c]-1,2,5-thiadiazole 1,1-dioxide (1d), 3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide (2a) and 4-ethoxy-5-methyl-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide (2b)], with reagents possessing two nucleophilic nitrogen atoms (urea, N,N'-dimethylurea, thiourea, N-methylthiourea, Nethylthiourea, N-allylthiourea, N,N'-diethylthiourea, N,N'-diphenylthiourea, dithioxamide and sulfamide), were followed by cyclic voltammetry (CV) and UV-visible spectrophotometry in aprotic solvent solution. The products were isolated, characterized by IR, H-1 NMR and C-13 NMR methods and their structure was confirmed by single-crystal x-ray diffraction. Several substrate-nucleophile combinations (1a-d and 2a with some ureas and thioureas) reacted to give good yields of new compounds formed by the addition reaction of the two nitrogen atoms of the nucleophile to the two >C=N- double bonds of the 1,2,5-thiadiazole 1,1-dioxide ring. Some systems (1a-dithioxan-Lide and 2b-thiourea) did not react, whereas in others (e.g. 1a-sulfamide) a monoaddition equilibrium reaction was observed. Copyright (C) 2004 John Wiley Sons, Ltd.